[mpetrov]

Sticky load balancing was a deal breaker for us when we built the https://map.couple.me visualization with socket.io. At the last minute I just pulled older browser support and left it with raw websockets instead of socket.io because the cluser module couldn't be used otherwise.

We had two issues with sticky load balancing:

1. AWS ELB had to run in TCP mode (for websockets) which meant no stickiness

2. Within each instance we have a node-cluster running to utilize multiple CPUs and putting haproxy with stickiness there increased complexity

We could avoid using the ELB but then you lose the ability to use an EC2 Auto Scaling group, introducing significant admin overhead.

Ultimately we didn't need the nodes communicating between each other (it's a one way stream from us to the client) so raw websockets ended up being the simplest solution.